• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.369-375
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• 1991

A series of in vitro incubation studies with washed rumen bacteria were conducted to determine the influence of incubation time and concentrations of peptides, alanine, ammonia nitrogen and carbohydrate on the rate of peptide disappearance and on bacterial growth. Disappearance rate of tri-alanine (ala3) under various conditions was between 30.6 and $58.2mg\;hr^-$ per gram bacterial dry matter. Ala3 was removed from the incubation medium in an almost linear fashion as incubation time and ala3 concentration was increased. Washed rumen bacteria utilized ala3 faster than di-l-alanine (ala2) at all concentrations. Adding 9mM carbohydrate significantly increased ala3 disappearance, but level of ammonia nitrogen had no influence on ala3 disappearance. The presence of alanine in the medium significantly lowered ala3 utilization by rumen bacteria. Bacterial dry matter and nitrogen growth yield were not influenced by alanine and peptides when incubation medium already contained a sufficient level of ammonia nitrogen. Increased ammonia nitrogen in the presence of ala3 did not stimulate bacterial growth. Carbohydrate significantly increased bacterial dry matter and nitrogen growth as expected. Results indicate that the rate of peptide utilization by rumen bacteria may be altered by type and concentration of peptides, and energy supply, and this may be mediated through changes in numbers and type of bacteria.

• Korean Journal of Environmental Agriculture
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• v.12 no.3
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• pp.281-297
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• 1993

Nitrogen is an element required to meet optimal plant growth. However, when it was applied (as chemical fertilizer or animal waste) more than the demand of plant and managed it unreasonably can be accumulated in subsoil and leached from soil system. Nitrogen also can be act as an pollutant to soil and water through water contamination if its concentration exceed the critical level. The concentration and downward movement of nitrate in soil is influenced by cultural practices and soil properties. High level of nitrate nitrogen in drinking water is harzadrous for animal and human health, especially for infants and the restoration of the quality of groundwater is impossible by now. Therefore it is the only way to prevent from leaching of nitrate nitrogen to keep the quality of groundwater as vital water resource. The aims of the presentation of this review paper are to understand the relationship between agricultural practices and the concentration of nitrate nitrogen in groundwater and to suggest further informations for the rational management methods to reduce the leaching of nitrate nitrogen in soil.

• Journal of Nutrition and Health
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• v.1 no.1
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• pp.19-25
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• 1968

In order to study the effect of source and level of the commonly used dietary fats on growth and metabolism of rats fed on low protein diet (rice diet) the weaning white rats were fed on various different experimental diets (see tables 1 and 2) during 11 weeks. The observations were made as follows : 1. Growth: (see table 3 and figures 1-9) In all dietary fats, among the 3 levels, 5% fat level is the best. Especially, the perilla oil group was remarkably good. 10% and 20% fat levels impaired the growth, consequently the growth rates of both 10% and 20% fat level groups were worse than those of Basal group (no fat added). However, 10% and 20% fat levels did not impaired the growth of VII group (10% soy flour added) In 5% fat level, the growth was good in sequence of perilla oil, tallow, sesame oil, soy oil and lard. 2. Feed consumption: (see table 3) In 20% fat level, the feed consumption was lowered. Generally, the feed consumption rate was proportional to the growth rate. In feed efficiency, 5% fat level was the best. 3. Liver weight: (see table 4) In liver weight per 100 G body weight, 20% fat level was the largest. This may be due to the poor body growth and liver fat accumulation. 4. Liver nitrogen: (see table 4) Generally, lower fat level groups showed liver nitrogen. Liver nitrogen is low in the groups of 20% fat level. 5. Liver fat: (see table 4) Generally, higher fat level groups showed higher liver fat. 6. Serum cholesterol: (see table 5) Generally, higher fat level groups showed higher serum cholesterol. Lard, sesame oil, and tallow groups showed higher level and soy oil and perilla oil groups showed lower level. Especially, perilla oil group showed remarkably lower level and VII group (10% soy flour added) showed lower level than VI group (same fat but no soy flour added).

• KSBB Journal
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• v.13 no.3
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• pp.325-330
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• 1998

The methylotrophic yeast, Pichia pastoris, is known to be a potential host to offer many advantages for production of recombinant proteins. Fermentation parameters were optimized to enhance the heterologous ${\beta}$-galactosidase productivity with P. pastoris. Optimum concentration of methanol, used as inducer, was observed to be 8 g/L and the extent of repression of AOX1 promoter by glycerol was lower than by glucose. The degradation of the gene product ${\beta}$-galactosidase by protease was inhibited as the pH increased from 5 to 8 and the yeast extract(1%) as nitrogen source increased expression level 4 times higher compared to yeast nitrogen base(1%) as nitrogen source increased expression level 4 times higher compared to yeast nitrogen base(1%). Induction method, in which methanol is just added to fermentation medium without centrifugation, was found to be as much effective as the one with centrifugation.

• Journal of Plant Biology
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• v.27 no.4
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• pp.253-261
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• 1984

Leaf discs isolated from the pea seedling grown in nutrient solution containing 5mM ammonia or nitrate exhibited a half level of photorespiration as compared with the nitrogen free control. The manifestation of the ammonia effect appeared somewhat earlier than that of nitrate effect, but this difference subsided as the culture periods was extended. The total amount of ${CO}_2$ fixed by leaves from nitrogen-supplemented seedlings showed approximately 1.5 fold increase over the control with the ammonia effect being manifested earlier than the nitrate effect. The activities of peroxisomal serine: glyoxylate aminotransferase were always higher with ammonia than nitrate, the two types of nitrogen source, however, had similar effect on conversion rate of glyoxylate into glycine. These results indicate that exogenous ammonia does not act directly as an effector of this aminotransferase in vivo. But changes in the level of the pool size of glycine and serine, both of which are the intermediates of photorespiratory process, suggest that exogenous ammonia inhibit the transformation of serine from glycine metabolically.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.2
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• pp.89-97
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• 1992

This experiment was attempted to investigate the effects of growing stage, cutting frequency and the level of nitrogen fertilization on the change of carbohydrate reserves in reed canarygrass(Pha1aris arundinacea L.). The results obtained were as follows: The amount of carbohydrate reserves appeared to markedly decrease up to critical level after the cutting in hot and dry weather season. During the growing stage, the amount of carbohydrate reserves decreased just after the cutting and also during the period of flourishing elongation of reed canarygrass. However, it began to increase sharply from the end of September for wintering. Two cutting system showed the highest mean value(19.53 %) of carbohydrate reserves and those of three, five and four cutting system was 15.32 %. 14.73 %, and 14.60 % respectively. Reed canarygrass with no nitrogen fertilization resulted in 17.17% of carbohydrate reserve, however there was no singificant difference among various levels of nitrogen fertilization. In respect of regrowth. 3 cutting system showed the most effective cutting frequency, however 4 or 5 cutting system had a decreasing tendency of regrowth.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.3
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• pp.384-394
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• 2001

In order to prevent pollution from animal waste, P, N and pharmacological level minerals should be properly managed. Microbial phytase has been used successfully to control P excretion. Activity of natural phytase in certain plant feedstuffs is high enough to be considered in feed formulation. Nitrogen control can be achieved through amino acid supplementation and protein restriction in the diet. Supplementation with carbohydrases reduces output of excreta as well as N. Ammonia release from the manure could be reduced by using a low crude protein diet along with the supplementation with probiotics products. Excretion of minerals used at pharmacological level can be reduced by using chelated forms. Cu and Zn in the form of methionine chelate have been successfully used in the broiler and pig diets.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1009-1016
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• 2012

The purpose of this study was to determine the effects of organic fertilizers on soil properties and growth and quality of melon. Organic fertilizer was applied in soil at the rate of 0, 0.5, 1, 2N according to Rural Development Administration guideline in Korea. The fertilizer had no effects on plant growth-rate parameters, including plant height, leaf number, and leaf size. There were minor effects on the fruit quality parameters such as fruit weight, fruit length, fruit width, placenta and seed weights, sugar content, and starch content. Ascorbic acid level was decreased as fertilizer level was increased. The level of nitrate in groundwater increased with increased levels of N.

• Journal of The Korean Society of Grassland and Forage Science
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• v.10 no.2
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• pp.84-88
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• 1990

This experiment was conducted to evaluate the effect of cutting frequency and nitrogen fertilization on $(NO_3$-N leaching losses under 12 years mixture permanent meadow, The results of this study were summarized as follows: 1. There was no difference in the $(NO_3$-N content of soil water within 1 m soil depth during the whole experimental period. It means that the content of $(NO_3$-N leaching losses was not influenced by botanical composition, cutting frequency and nitrogen fertilization in this experiment. 2. The level of $(NO_3$-N content during the whole experimental period was not in excess of 0.5 ppm level.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.639-643
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• 2011

Zinc oxide as an optoelectronic device material was studied to utilize its wide band gap of 3.37 eV and high exciton biding energy of 60 meV. Using anti-site nitrogen to generate p-type zinc oxide has shown a deep acceptor level and low solubility. To increase the nitrogen solubility in zinc oxide, group 13 elements (aluminum, gallium, and indium) was co-added to nitrogen. The effect of aluminum on nitrogen solubility in a $3{\times}3{\times}2$ zinc oxide super cell containing 72 atoms was investigated using density functional theory with hybrid functionals of Heyd, Scuseria, and Ernzerhof (HSE). Aluminum and nitrogen were substituted for zinc and oxygen sites in the super cell, respectively. The band gap of the undoped super cell was calculated to be 3.36 eV from the density of states, and was in good agreement with the experimentally obtained value. Formation energies of a nitrogen molecule and nitric oxide in the zinc oxide super cell in zinc-rich conditions were lower than those in oxygen-rich conditions. When the number of nitrogen molecules near the aluminum increased from one to four in the super cell, their formation energies decreased to approach the valence band maximum to some degree. However, the acceptor level of nitrogen in zinc oxide with the co-incorporation of aluminum was still deep.